World of Warcraft has been a goldmine for Blizzard, but that can't be all it's working on. Back before WoW ate countless lives with its grinding, raiding, and leveling, Blizzard was known for awesome strategy games such as Warcraft and Starcraft, awesome action RPGs such as Diablo and Diablo II, and even awesome platform-puzzlers such as The Lost Vikings. All of these games seem to have been left at the wayside while Blizzard focuses on keeping its WoW servers up and running, and its players chipping in their monthly fee.

Still, rumors are fun, and it'll be interesting to see just what Blizzard might be working on. The company has a few great universes and a superlative back catalog of games. Here's a look at what Blizzard might be developing. Keep in mind that this is all speculation and shouldn't be taken seriously until Blizzard coughs up some concrete information.

World of StarcraftThe pitch: Terrans, Zerg, and Protoss continue their war with each other across different planets in a sci-fi MMORPG with plenty of cross-faction PVP action.
The case for:Starcraft is one of Blizzard's most beloved properties, and to this day it's an incredibly popular game. Tons of sci-fi fans would probably love to see Starcraft get the World of Warcraft treatment. Blizzard already has MMO infrastructure in place, so it probably wouldn't be nearly as complicated or time-consuming a development process as World of Warcraft.The case against: Sci-fi MMOs tend to be tricky, with a lot more high-tech stuff that would be difficult to translate from RTS. Blizzard will have to get pretty creative with missions, since there are only so many Zerg holes a marine can clean out before he just gets sick of it.
The likelihood: Pretty good. Blizzard's already proven it can translate a great RTS property into a great MMO, and World of Starcraft would eat up all the Star Trek/Star Wars/Stargate nerds who are turned off by Warcraft's fantasy setting.

Starcraft 2The pitch:Starcraft returns to the RTS form with better graphics, more units, deeper strategy, and possibly an additional faction or two.
The case for: The game is nine years old and people still play it to this day. A zerg-rushing celebration with modern graphics would be a sure hit.
The case against: Command and Conquer 3 and Supreme Commander are already wrestling for to billing in the sci-fi RTS genre, a genre that has shrunk in popularity in the last decade. It'll be pretty crowded in there, and Starcraft 2 will be showing up late to the game.
The likelihood: Pretty good. If done right, Starcraft 2 could completely bowl over Command and Conquer 3 and Supreme Commander and reclaim Blizzard's former title as king of the RTS.

Diablo 3The pitch: The forces of hell are trying to take over the world once again, and you need stop them by creating a hero from a wider selection of classes and specialties, with bigger dungeons and more complex quests.
The case for:Diablo II was one of the most popular games of its time, and the addictive properties of leveling up, collecting equipment, and hacking through hundreds of demons simply doesn't get old.
The case against: Most of the developers of Diablo and Diablo II are working on Flagship Studios' Hellgate: London. Blizzard might not be able to make the same Diablo we knew and love.
The likelihood: Slim. World of Warcraft already satisfies most gamers' need for grinding, killing, and item collecting. Diablo 3 would add a little more action to the same basic, polished formula, probably without the lucrative monthly fee.

Warcraft 4The pitch: Like World of Warcraft, only an RTS game.
The case for: There's a big fantasy RTS-shaped hole in today's game market that would easily be filled by Blizzard's biggest IP, Warcraft. It started as an RTS and would make sense to continue as one.
The case against: It would break WoW players out of the game with the inevitable major, world-changing storyline. Warcraft's story is already evolving through WoW's updates and expansions, and the sort of changes Warcraft 4 would probably make to the Warcraft universe would seriously unbalance that.
The likelihood: Slim, for now. When WoW starts to run down and Blizzard gets to work on World of Warcraft 2, it will be more likely for a Warcraft 4 to bridge the two MMO worlds.

The Lost Vikings 3The pitch: Time-traveling Norsemen Erik, Baelog, and Olaf are back, and they're still trying to get home.
The case for:The Lost Vikings were awesome.
The case against: It's not Blizzard's most recognized property, and they've already gotten a respectable cameo in the Uldaman dungeon in World of Warcraft. It probably wouldn't translate well to 3D and modern graphics.
The likelihood: Not gonna happen. They might keep on making cameos, but we're not going to see a new, modern Lost Vikings game any time soon. Maybe a remake or two on the Nintendo DS or PSP, but that's the best we can hope for.

And before any of you ask, I didn't list Starcraft: Ghost because it's cancelled. It's not coming out. You're not going to be able to play it. It is not fated to be released on any platform. That is all.